1. Field of the Invention
The present invention relates to a disk device, in particular, a disk device in which a turntable, coacting with a clamper to clamp a disk and rotating the disk, is mounted on a traverse chassis and in which a countermeasure for suppressing reading error of the disk due to self-induced vibration of the traverse chassis is applied.
2. Description of the Related Art
With this type of disk device, one end of the traverse chassis is supported on a fixed frame (loader chassis), and the traverse chassis is enabled to tiltingly move (enabled to move reciprocatingly) along a rectilinear path with a position of support by the fixed frame as a pivot. The turntable is mounted, along with an optical element, such as an optical pickup, etc., on the traverse chassis, and when the traverse chassis moves onward along with the turntable, the disk, mounted on the turntable, is clamped by coaction of the turntable and a clamper, attached to the fixed frame and waiting at a fixed position. The disk, clamped by the clamper and the turntable, rotates together with the turntable, and during the rotation, the disk is optically processed by the optical pickup.
With this type of disk device, there is known a configuration employing a cam mechanism, to be described below, as a means for making the traverse chassis undergo reciprocal movement (see JP-A-2003-223776). This is a schematic exploded perspective view of a cam mechanism 10 described in JP-A-2003-223776.
FIG. 5 is a schematic front view of the cam mechanism 10 of a disk device described in JP-A-2003-223776. The cam mechanism 10 is constituted of a follower 20, disposed on the traverse chassis (not shown), a cam plate 30, moved forward and in reverse as indicated by arrows X in a direction orthogonal to a direction of reciprocal movement of another end of the traverse chassis, a cam groove 31, formed in the cam plate 30 and making the follower 20 slide to make the other end of the traverse chassis move reciprocatingly along a rectilinear path, and an auxiliary guiding member 40, having straight guiding surfaces 41 that make the follower 20 slide when the cam plate 30 is moved forward and in reverse to guide the reciprocal movement of the follower 20. The cam groove 31 of the cam plate 30 includes a horizontal first riding surface 32, onto which the follower 20 rides at its onward movement limit position, a horizontal second riding surface 33, onto which the follower 20 rides at its return movement limit position, and an inclined surface 34, making the first and second riding surfaces 32 and 33 continuous.
In the disk device, including the cam mechanism 10, when the turntable, mounted on the traverse chassis, and the clamper coact to clamp a disk, the follower 20 of the cam mechanism 10 that rides on the first riding surface 32 of the cam groove 31 is clamped by the guiding surfaces 41 as shown in FIG. 5. The follower 20 and the other end of the traverse chassis provided with the follower 20 are thus provisionally positioned in the reciprocal movement direction (vertical direction), indicated by arrows A in the figure, and a direction (left/right direction), indicated by arrows B in the figure and orthogonal to the reciprocal movement direction of the traverse chassis.
With the cam mechanism 10 described with reference to FIG. 5, for a vibration absorbing action by an elastic member 23 of the follower 20 to be exhibited with good efficiency, the follower 20 of the cam mechanism 10, riding on the first riding surface 32 of the cam groove 31, is desirably clamped by the guiding surfaces 41 and positioned accurately in the mutually orthogonal directions indicated by the arrows A and B.
However, because gaps that are essential for allowing smooth movement of the follower 20 and gaps, etc., due to manufacturing errors are present between the guiding surfaces 41 and the follower 20 of the cam mechanism 10 riding on the first riding surface 32 of the cam groove 31 and between the follower 20 and the cam groove 31, the follower 20 is not accurately positioned without play in the mutually orthogonal directions indicated by the arrows A and B. Thus with the cam mechanism 10, when the traverse chassis undergoes self-induced vibration during disk rotation, the entirety of the follower 20 may vibrate and the vibration absorbing action by the elastic member 23 of the follower 20 may not be exhibited efficiently. When the follower 20 thus undergoes self-induced vibration and the vibration absorbing property of the elastic member 23 degrades, the rotating disk vibrates, causing optical reading errors by the optical pickup to occur readily and thus image distortion, sound skipping, etc., to occur readily.
This problem is known to occur especially readily during reproduction of a disk with a mass eccentricity, etc. There is also a possibility for optical reading errors occurring readily due to deformation of the first riding surface 32 of the cam groove 34, the guiding surfaces 41 of the auxiliary guiding member 40, etc., caused by influence of heat generated by the vibration of the follower accompanying the self-induced vibration of the traverse chassis, and it is known that the possibility of this occurring is especially high under a high temperature environment, such as 65° C. temperature and 80% humidity, or after high temperature storage, such as 120 hours of storage under 65° C. temperature and 80% humidity.